At the present time, there are various types of input devices for conveying the intention of a user to a computer. For example, generally data etc. is input using a keyboard. In addition, there are also voice-activated input devices, but there are limits to the accuracy of voice recognition and these are not yet in broad use.
These input devices, however, mainly input data relating to text data. It is often also necessary to input graphic data. Further, when inputting graphic data, sometimes the data is input while drawing it. As the input devices used for this, tablets are the mainstream.
Such a tablet will be explained with reference to FIG. 16.
A tablet, like a keyboard or a mouse, is connected to a computer. When the tracing a figure on a screen 101 provided at the tablet by the tip of a pen housing a coil etc., the coordinates of the points traced by the tip of the pen are detected and the coordinate data sent to the computer. The display screen of the computer displays the path of the points traced in accordance with display positions based on the coordinate data.
Conductor patterns 103 are laid in a matrix on the screen 101 of the tablet. A Y-coordinate scan circuit 104 and an X-coordinate scan circuit 105 are provided for determining the coordinates of the pen 102 from the voltage generated at the conductor patterns 103. The pen 102 attached for tracing a figure on the screen 102 houses a coil for generating an electromagnetic wave.
When a user moves the tip of the pen 102 on the screen 101, an electromagnetic wave is generated from the coil in the pen 102 and an electromotive force is generated by Faraday's law of electromagnetic induction at the conductor patterns 103. The Y-coordinate scan circuit 104 and the X-coordinate scan circuit 105 find the positions of the coordinates relating to the tip of the pen 102 based on the electromotive force generated in the conductor patterns 103.
A tablet is configured separate from the computer. As another type of input device, however, there is a touch panel built into the display screen of a computer. FIG. 17 shows the configuration of this touch panel.
The touch panel 111 is placed on the display screen of the computer by adhesion etc. The touch panel 111 is formed with a large number of transparent switches SWmn in a matrix. These are arranged so that the coordinates of the display screen of the computer and the coordinates of the touch panel 111 match.
When a user presses any position of the touch panel 11 by his or her finger, a pen, etc., the switch SWmn at the pressed location closes. An X-coordinate switching detection driver 112 and Y-coordinate switching detection driver 113 can detect the closed state of the switch SWmn so as to specify the XY coordinates of the pressed point.
While there are input devices configured like the above, figures are mainly drawn using tablets, while simple selection operations etc. are performed using touch panels.
A touch panel is either adhered to the display screen of a display device or placed in a state covering the screen, so is made thin. With a touch panel, the cost rises the larger the screen. Further, it has to be installed on the display device, so the visibility of the display information is impaired. Further, the panel is directly pressed by the finger, pen, etc., so is easily damaged or deteriorated.
On the other hand, a tablet comprises a board shaped like a mouse pad in which is built conductor patterns, scan circuits, and other coordinate detection devices and uses a pen instead of a mouse. With a tablet, the coordinates on the display screen of the computer and the coordinates on the tablet have to be matched. The work for matching them is performed by the user. This work requires considerable technical skill and experience.
Further, in recent years, tablets have been built in at the back side of LCD panels to allow intuitive use like with a touch panel. Since these are built-in types, however, it is not possible to add this function to existing hardware. Further, when building in a tablet, it is necessary to match the coordinates on the display device and the coordinates on the tablet. Further, the tablet itself has to be made thin in order not to detract from the paramount feature of LCDs—their thinness. In this way, a high manufacturing technology is demanded and the cost become high.
Therefore, an input device which enables intuitive input work on a display screen and can be added even to existing computer hardware is sought. Further, an input device which enables easy determination of coordinates relating to a point indicated on a display screen is required.